GNU testsuite comparison:

Skipping an intermittent issue tests/misc/stdbuf (passes in this run but fails in the 'main' branch)

GNU testsuite comparison:

Skip an intermittent issue tests/timeout/timeout (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/misc/stdbuf (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/misc/tee (passes in this run but fails in the 'main' branch)

As an extra remark, please stash your "clippy fixes" commit in the first one.
It is useful to split implementation and tests, and we shall keep both commits in the main branch, if we ever need to revert/check something, but clippy fixes are not useful to keep track of.

Thanks !

* What locale did you use to perform your tests ?

Here's the locale I was using for all tests:

% locale
LANG="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_CTYPE="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_ALL=

* Can you check there is no discrepancy with GNU's `fold`with `LC_ALL` being `en_US`, `en_US.UTF-8`, `C` and `C.UTF-8` ?

I've tried all three of my new tests with those locales and they all give the exact same output as each other (and as the coreutils fold).

I also consolidated all the code changes into one commit and re-pushed, so the commits history should be simpler now.

GNU testsuite comparison:

Skipping an intermittent issue tests/misc/stdbuf (passes in this run but fails in the 'main' branch)

Thank you for your contribution !